A Near-Infrared Fluorescent Probe for the Detection of Mitochondrial Viscosity and its Application in the Imaging of Alzheimer's Disease Mice Brain

Abstract

Viscosity is an important part of the cell microenvironment. Abnormal viscosity in the microenvironment is related to many diseases such as tumors, fatty liver and Alzheimer's disease. Accumulated β-amyloid (Aβ) fibrils and plaques are key pathological features of Alzheimer 's disease, which can lead to severe neurotoxicity and cognitive and behavioral disorders. In this work, a near-infrared fluorescent probe (G) based on anthraquinone-quinolinium dye was constructed to detect viscosity. When the viscosity of the medium is high, the free rotation of the single bond is suppressed and the fluorescence intensity is enhanced. The probe shows high selectivity for viscosity. It is worth noting that probe G has a long excitation wavelength (640 nm) and emission wavelength (825 nm) with a large Stocks shift of 185 nm. At the same time, probe G is not only a positively charged molecule that can target mitochondria. In addition, probe G is not only used to detect the viscosity of Aβ protein in vitro, but also image the abnormal viscosity of Aβ protein in the brain of Alzheimer's disease mice.

Note:
Funding Information: This work was supported by National Natural Science Foundation of China (Nos. 22474068, 22004078 and 22074074), and Youth Innovation Team Development Program of Shandong Higher Education Institutions (No. 2022KJC004), and the Taishan Scholar Program of Shandong Province (tstp20231227), and Natural Science Foundation of Shandong Province (No. ZR2024QB063), and Natural Science Foundation of Qingdao (No. 23-2-1-175-zyyd-jch).

Declaration of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Ethics Approval Statement: Animal experiments were carried out according to the guidelines for experimental animal care and use of Qingdao University of Science and Technology and was approved by the Medical Ethics Committee of Qingdao University of Science and Technology.

Keywords: NIR fluorescent probe, TICT, mitochondrial viscosity, living cell imaging, AD mice brain imaging